What is an engine? Citing Merriam Webster[1]:
>3a: something used to effect a purpose
So yes, an engineer can make implements of war among many other implements. The people who actually wage war are called other things.
[1]: https://www.merriam-webster.com/dictionary/engine
Also, you've inverted the etymology. Engines are named after the ingenuity of their makers.
What is an engine? Citing Merriam Webster[1]:
>3a: something used to effect a purpose
So yes, an engineer can make implements of war among many other implements. The people who actually wage war are called other things.
[1]: https://www.merriam-webster.com/dictionary/engine